A known type of aircraft brake system comprises a plurality of stator disks mounted to a fixed portion of a wheel support and a plurality of rotor disks connected for rotation with an aircraft wheel which rotors extend into spaces between the stators. When braking is required, a piston mounted next to this stack of disks is extended to compress the stack and force the rotors and stators into contact, thus slowing the rotors and the wheel attached thereto.
Rotor drive keys are mounted on the interior of the aircraft wheel to engage the rotors and cause the rotors to rotate with the wheel. These drive keys are essentially metal bars that run parallel to the axis of the wheel and perpendicular to the major faces of the rotor disks. Each rotor disk includes a plurality of notches along its outer periphery through which the drive keys extend, and this notch-and-key arrangement circumferentially couples the rotors to the wheel. Similarly, splines are provided on the torque tube supporting the stators that engage notches on the inner peripheries of the stator disk to help fix the stators circumferentially relative to the torque tube.
Brake rotors and stators are sometimes formed from steel. However, it is becoming common to form the rotor and stator disks from carbon materials. These materials may comprise, for example, carbon embedded in a carbon fiber matrix, which material may be referred to generically as “carbon” or “carbon-carbon.” Carbon brake disks may also include notches in their outer peripheral walls for accommodating drive keys and in their inner peripheral walls for accommodating torque tube splines. However, because carbon can be more fragile than steel, these notches also typically include inserts to better distribute the load from the drive keys and/or splines to the rotor or stator and to reduce wear on the carbon brake disks. These inserts are typically formed from steel.
A conventional rotor and rotor insert are illustrated in FIG. 10 which shows a rotor 200 having first and second sides 202, only one of which is visible in FIG. 10, and an outer peripheral wall 204 connecting the sides 202. A notch 206 extends into peripheral wall 204 for receiving a drive key (not shown). The notch has a bottom wall 208 and first and second side walls 210 extending away from bottom wall 208. A rotor insert 212 is mounted in notch 206 and includes a bottom 214 overlying notch bottom wall 208 and first and second legs 216 extending from insert bottom 214 along notch first and second side walls 210. A retainer 218 overlies peripheral wall 204 and projects over the ends and sides of insert legs 216 to secure insert 212 against axial and radial movement with respect to the rotor disk. Rivets 220 pass through openings (not shown) formed in rotor 200 to secure the retainer 218 to both sides 202 of the rotor 200. In use, a drive key (not shown) running through notch 206 will contact insert legs 216 which in turn distribute the load from the drive key over the side walls 210 of the notch 206. Similar inserts may be provided in an inner peripheral wall of a stator disk and secured to the stator disk in a similar manner.
Inserts and retainers such as those described above perform in an acceptable manner. However, a typical rotor disk may have eight to twelve outer peripheral notches, and each retainer often requires about three rivets to secure. It is therefore necessary, in some cases, to drill about 36 openings, align those openings with openings in the retainers, and secure rivets in each of the openings. Similar difficulties are presented when installing inserts in stator inner peripheral walls. Such procedures add to the cost and complexity of rotor and stator assembly. It would therefore be desirable to reduce or eliminate the use of rivets when connecting inserts to rotor or stator disks.